AMD's Next-Generation Mobile Architecture Revealed: Griffin
by Anand Lal Shimpi on May 18, 2007 12:10 AM EST- Posted in
- CPUs
New Memory Controller
Although the underlying architecture of Griffin is K8 based, the memory controller takes a lot of cues from Barcelona/Phenom. There's a new DRAM prefetcher, similar but not identical to what will be in Phenom, but many of the efficiency improvements in the new desktop core will make their way to Griffin as well. Taken from our Barcelona architecture article:
"One strength of Intel's FB-DIMM architecture used in Xeon servers is that you can execute read and write requests to the AMB simultaneously. With standard DDR2 memory, you can do one or the other, and there's a penalty for switching between the two types of operations. If you have a fairly random mixture of reads and writes you can waste a lot of time switching between the two rather than performing all of your reads sequentially then switching over to writes. The K8's memory controller made some allowances for preferring reads over writes since they take less time, but in Barcelona the memory controller is far more intelligent.
Now, instead of executing writes as soon as they show up, writes are stored in a buffer and once the buffer reaches a preset threshold the controller bursts the writes sequentially. What this avoids is the costly read/write switch penalty, helping improve bandwidth efficiency and reduce latency."
AMD did not make it clear whether Griffin also featured two independent 64-bit DDR2 memory controllers or a single 128-bit one. And, of course, as the memory controller is a part of the North Bridge it operates at a separate, lower voltage than the rest of the CPU cores.
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yyrkoon - Friday, May 18, 2007 - link
I can not help but think 'WHY' a laptop *NEEDS* more than one core on the CPU. Anyone claiming that their laptop is comparrible to the performance of a good desktop, is only kidding themselves. From my point of view, a laptop is a tool, used to do whatever you can not do on the desktop, for whatever reason ( travelling, and away, from your desktop, etc ). Yes, I understand that multiple core CPU have been availble in laptops for some time now, but that does not really answer my question. The point I am getting at here, is that if the laptop CPU could be made aroudn a single core, there should be plenty of room for other enhancements, and a potential for a lower TDP.The statement above, to me resembles something along the lines of the difference between USB v2.0, 400Mbit firewire , and syncronous/asyncronous read/write capabilities, there *HAS* to be a performance hit here . . . Who knows, maybe I am wrong ?
Justin Case - Sunday, May 20, 2007 - link
A second core does make a very significant difference in terms of system responsiveness, even if you rarely (or never) max out both CPUs. I started using dual-CPU systems about 8 years ago and never looked back.More and more people are using a laptop as their only PC, so that theory that laptops are just typewriters isn't true anymore. They used to be just typewriters because that was all they _could_ do.
With proper power management, a dual-core CPU can consume as little as a single-core one, for the same amount of work, so the only issue becomes the price of the chip itself. And since dual-core CPUs are so cheap, these days, there's really no reason not to have one.
Eris23007 - Friday, May 18, 2007 - link
My company issued me a laptop, complete with anti-virus, software firewall, and hard disk encryption preinstalled that I can't turn off. My system runs two antivirus scans a week on the whole hard drive (at about 4 hours each). Given that an antivirus scan requires considerable hard disk access, that means that in addition to the processor load for running the virus-scanning algorithms, there's also substantial load for decryption.
Unfortunately this laptop is a single-core Pentium M - no Core 2 Duo for me. My friend who hired on a little after I did got the Core 2 Duo version. The difference is astounding. My laptop (on XP, of course) has significant usability constraints - even the UI just isn't very responsive because of all the crap running in the background.
I would *LOVE* to have an extra core around, dedicated to handling this bullcrap. It would make a tremendous difference in my ability to actually "get work done" when my system would otherwise be busy running all this junk.
I'm aware that the extra core wouldn't improve the hard disk situation - but it would DEFINITELY help a WHOLE lot.
ADDAvenger - Friday, May 18, 2007 - link
There's more people than you'd think who have a laptop as their only computer, and I am one of them. Yeah a laptop doesn't NEED dualcore, but believe me, it does make more of a difference than you want to give it credit for. I'm in college and take notes on this thing all day, a desktop just wouldn't work for me, and I just don't have the money to have both right now.Wolfpup - Friday, May 18, 2007 - link
Totally agree. I can't wait for quad core laptops. And yes, I intend to use my laptop as my only computer.sprockkets - Friday, May 18, 2007 - link
because it was demonstrated that adding another core did not make any difference in battery life while increasing performance.JackPack - Friday, May 18, 2007 - link
The new Intel Merom M0 stepping processors already supports something similar. With single threaded apps, one core goes down to C3 while the other speeds up to a turbo frequency (bin + 1) while staying below or at the specified TDP.
goku - Friday, May 18, 2007 - link
I agree with this as well. People really expect laptops to be something that can do everything and it really is unreasonable. That said, AMD and Intel are making their computers more powerful so that people can start using laptops exclusively as that is the market trend, to go away from desktop machines.I'm wondering if AMD supports completely turning off a core and having it run in single core operation as I'd think running in single core mode with a slightly higher clock speed (if at all) would be more power efficient than having two slower cores running simultaneously. No need to have two cores running when you're just typing in MS word. It'd also be nice if intel and AMD would support far slower clocks speeds as IIRC the minimum clock speed increased from 600mhz on the Dothan and Banias machines to 800mhz on newer machines.
If I could get my laptop to downclock to 100mhz when I'm typing in Word and reduce the voltage considerably, I bet you'd see a much higher jump in battery life. But with vista being so bloated today, the computer would probably never downclock to a speed as low as that since XP and vista seemingly are always busy.
CrystalBay - Friday, May 18, 2007 - link
Kinda sounds like Barcelona, is not the panacea people were hoping for...Hulk - Friday, May 18, 2007 - link
Anand pretty clearly stated that Griffen is not based on Barcelona but on K8.I'm not really getting how this strategy will help AMD in the mobile market though. The current K8 core is getting pasted by C2D today clock-for-clock. And from what I just read I don't think the improvements made to create Griffen will enable to catch up to C2D IPC-wise.
Add to that the fact that by the Griffen release time Penryn will be widely available at 45nm. More power efficient than current mobile C2D offerings, faster, and with better IPC.
Like I said, I don't get it?